1. Field of the Invention
The present invention relates generally to a planarization apparatus, specifically to a planarization apparatus which performs a grinding process for a back face of a semiconductor wafer in a manufacturing process.
2. Description of Related Art
In a planarization apparatus of this type, dressing of a grinding wheel and a polishing pad is performed using a dressing board. The dressing board is made of a dressing stone, for dressing the grinding wheel or the polishing pad, processed in a disk shape like the wafer, and the dressing board is mounted on a table for holding the wafer in order to be used. The dressing board is mounted on the table just like the wafer to be processed, and the grinding wheel or the polishing pad is rotated and pressed against the dressing board whereby the grinding wheel or the polishing pad is dressed.
In a conventional art, the dressing is performed by an operator. In other words, the operator mounts the dressing board on the table, and after the dressing, the operator withdraws the dressing board from the table, all manually.
However, when performing the conventional dressing by the operator manually, the process is interrupted if the dressing is required during one lot, and the process has to be restarted after the dressing; as a result, throughput efficiency is lowered.
On the other hand, since IC cards have come into demand, a planarization apparatus such as a back grinder and a polisher which grinds and makes the back face of the wafer thin processes the wafer as thin as 30{grave over (1)} m like paper. Hence, sharpness of the grinding wheel or a condition of the polishing pad directly affects processing accuracy. Because of that the grinding wheel or the polishing pad must be maintained in a fine condition; in the conventional art, however, if the operator performs manually the dressing, there is inconsistency in time and accuracy; in addition, other errors will occur.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of a planarization apparatus which can automatically dress the grinding wheel or the polishing pad.
In order to achieve the above-described objects, the present invention is directed to a planarization apparatus, comprising: a table which holds a first face of a wafer by suction; one of a grinding wheel and a polishing pad, the table and the one of the grinding wheel and the polishing pad being moved relatively close to each other to press the one of the grinding wheel and the polishing pad on a second face of the wafer on the table and being rotated relatively to each other so as to process the second face of the wafer on the table; a dressing board, the one of the grinding wheel and the polishing pad being, when the table holds the dressing board instead of the wafer, pressed on the dressing board on the table so as to dress the one of the grinding wheel and the polishing pad; a stocker which stocks the dressing board; a transporting device which picks up the dressing board from the stocker, transports the dressing board to the table, withdraws the dressing board from the table, and stores the dressing board in the stocker; and a controller which controls the transporting device and executes dressing of the one of the grinding wheel and the polishing pad.
According to the present invention, when the grinding wheel or the polishing pad is dressed, the transporting device picks up the dressing board from the stocker, and transports the dressing board on the table. Then, the rotating grinding wheel or the rotating polishing pad and the table are moved relatively close together so that the dressing board is pressed against the grinding wheel or the polishing pad, thereby the grinding wheel or the polishing pad is dressed. After the dressing is completed, the transporting device withdraws the dressing board from the table and stores the dressing board in the stocker. Thus, the grinding wheel or the polishing pad can be automatically dressed.